Indwelling pleural catheter efficacy and safety in malignant vs. non-malignant pleural effusions: a prospective study

Abstract

Background

Indwelling pleural catheters (IPCs) are used to manage refractory pleural effusions (PEs), including malignant (MPE) and non-malignant pleural effusions (NMPE). This study evaluates IPC efficacy and safety, focusing on pleurodesis success, symptom relief, recurrence, survival, and complications.

Methods

A prospective cohort study of 74 patients (62 MPE, 12 NMPE) who underwent IPC insertion between 2019 and 2024 at a tertiary teaching hospital. Patients were followed for at least 12 months. The primary outcomes were symptom relief and successful pleurodesis. Secondary outcomes included the duration of IPC placement, time to pleurodesis, recurrence rates, complication rates, and overall survival.

Results

Pleurodesis was achieved in 32% of patients, lower in MPEs (28%) than NMPEs (50%) (p = 0.02). Mean IPC duration was 10.2 weeks (MPE: 10.7, NMPE: 7.5 weeks). Symptom relief was reported in 85%, with no significant difference between groups. Recurrence occurred in 3% of patients, all within the NMPE cases. Complications included catheter blockage (16%), chest pain (13%), loculation (9%), and pleural infection (9%), with no significant differences between groups. MPE patients had significantly lower survival at 3, 6, and 12 months (p < 0.05). IPC duration was not linked to survival (p = 0.93).

Conclusion

IPCs provide symptom relief and facilitate pleurodesis, though success is lower in MPEs. Complications are comparable between groups, supporting IPCs as a management option for both MPE and NMPE. Further research is needed to optimize IPC use and identify predictors of pleurodesis success.

Trial registration

Retrospectively registered.

Graphical Abstract

Background

Pleural effusions (PEs) represent a frequent encounter in emergency departments, with heart failure (HF), pneumonia, and malignancy being the most common underlying etiologies [1]. PEs are broadly categorized as transudative or exudative, depending on the mechanism of fluid accumulation. Transudative effusions result from an intact capillary membrane and increased hydrostatic pressure, and may also occur due to reduced oncotic pressure such as in hypoalbuminemia, whereas exudative effusions arise from capillary injury secondary to inflammation or malignancy [2]. Thoracentesis offers a therapeutic option for PEs, but a significant proportion of effusions may be treatment-resistant or have rapid recurrence, causing discomfort and challenges for caregivers [3]. Malignant pleural effusions (MPEs) are a common complication of several cancers, including lymphoma, breast, lung, ovarian, and gastric cancers [4]. Among non-malignant refractory effusions, HF and hepatic hydrothorax are the most frequent etiologies [5].

Traditionally, the management of refractory pleural effusions (PEs) has relied on repeated thoracentesis. However, this approach presents several limitations, including increased patient discomfort, impaired quality of life, and higher complication risks like pneumothorax and hemothorax [6]. To address these limitations, pleurodesis emerged as a valuable therapeutic strategy. Pleurodesis traditionally involves chemical (sclerosing agents like talc) or surgical methods [4]. Talc pleurodesis, in particular, remains a cornerstone therapy for recurrent PEs. Nevertheless, its success rates vary significantly, with controlled studies suggesting 70–90% efficacy [7, 8], while real-world data report failure in up to one-third of patients even when guidelines are followed [9]. Additionally, both surgical and chemical pleurodesis are associated with potential adverse effects, including significant pain, fever, dyspnea, hypotension, and a higher risk of infection [10].

Indwelling pleural catheters (IPCs) have revolutionized the treatment landscape for refractory PEs. These thin, flexible silicone tubes were first approved by the US Food and Drug Administration (FDA) in 1997 for MPEs. Their use for non-malignant pleural effusions (NMPE) was not formally introduced into clinical practice and received FDA clearance until 2017 [11–13]. IPCs likely induce pleurodesis by triggering inflammation within the pleural space [14] and offer significant advantages, such as reduced hospital admissions, improved patient quality of life, and potentially decreased risk of pneumothorax and hemothorax compared to repeated thoracentesis [15]. These catheters offer several benefits, from symptom improvement to the potential for spontaneous pleurodesis in up to half of patients within 3 months of placement [15, 16].

While IPCs have historically been used for MPEs, their role in NMPEs is increasingly recognized. NMPEs refer to persistent pleural effusions that are unrelated to malignancy and refractory to conventional treatments. However, optimal patient selection and clinical outcomes with IPCs remain an area of ongoing research [17]. This study aims to evaluate the efficacy and safety of IPCs in both malignant and non-malignant pleural effusions, focusing on pleurodesis success, symptom relief, time to pleurodesis, recurrence post-removal, complication rates, and overall patient survival.

Materials and methods

Study design and ethics approval

This prospective cohort study was conducted at a tertiary teaching hospital on patients who underwent IPC (Rocket Medical) insertion for the management of refractory PEs. The study protocol was approved by the Institutional Research Ethics Board (IR.TUMS.IKHC.REC.1402.472) and adhered to ethical guidelines (Fig. 1).

Fig. 1.

Study Flowchart Illustrating the Process from Patient Screening and Selection to Data Analysis

Patient population and study criteria

All adult patients who underwent IPC placement between 2019 and 2024 were included in the study. MPEs were defined as pleural effusions associated with histologically confirmed malignancy, positive cytology for malignant cells, or recurrent exudative effusions with evidence of extrapleural malignancy. NMPEs were defined as pleural effusions with negative cytology and no underlying malignancy. IPC placement was considered only after failure of standard medical therapy and at least three therapeutic thoracenteses (Fig. 1). While the presence of trapped lung was not an exclusion criterion, no patients demonstrated radiologic or sonographic evidence of non-expandable lung at the time of catheter insertion.

Exclusion criteria

Patients were excluded from the study if they had undergone additional pleural interventions beyond repeat thoracentesis, declined participation, or had significant missing data that could affect outcome analysis. Moreover, in cases where multiple potential diagnoses were present, the clinician’s primary diagnosis was considered for classification (Fig. 1).

Intervention protocol

All IPCs were inserted using ultrasound guidance under local anesthesia by an interventional pulmonologist in the bronchoscopy unit. The procedures were conducted in an ambulatory setting, allowing for same-day discharge. Following insertion, vacuum bottles were used for pleural drainage. Initially, daily drainage was performed, transitioning to every other day once the output decreased to < 500 mL/day. If drainage remained < 50 mL/day for 2–3 consecutive weeks, a chest X-ray (CXR) and ultrasound were performed to assess for pleurodesis. If imaging confirmed pleural apposition with no evidence of fluid reaccumulation, IPC removal was scheduled. This definition was selected to ensure stability and reduce the risk of premature catheter removal and recurrence in routine outpatient practice. Patients and their caregivers received comprehensive training on drainage techniques and catheter care to facilitate home-based management, aiming to reduce hospital visits and improve patient autonomy (Fig. 1).

Data collection

Baseline demographic and clinical data, including age, sex, underlying diagnosis, and pleural effusion type (malignant vs. non-malignant), were collected at the time of IPC insertion. The duration of IPC placement and pleurodesis success were documented, along with complication rates, which included catheter tract metastasis, blockage, pneumothorax, hemothorax, subcutaneous emphysema, bleeding, infection, chest pain, malnutrition, dislodgement, fracture, and leakage. Additional outcome measures included symptom relief, time to pleurodesis, the need for subsequent procedures, post-removal recurrence, and overall patient survival. Patients were followed monthly on an outpatient basis for at least 12 months post-IPC insertion to assess long-term outcomes and monitor for recurrence of pleural effusion (Fig. 1).

Outcomes and definitions

The primary outcomes of this study were symptom relief following IPC insertion and successful pleurodesis. Symptom relief was defined specifically as improvement in dyspnea following IPC insertion. At each follow-up, patients or their caregivers were asked a standard question: ‘Has your breathing improved compared with before catheter insertion?’ (yes/no). Initial improvement in dyspnea was recorded as successful symptom relief. In patients who later experienced recurrent dyspnea due to effusion re-accumulation or disease progression, this was documented separately under recurrence or progression and was not considered a failure of the initial symptom relief outcome. Although no validated scale was employed, this approach was applied consistently to all patients irrespective of effusion etiology.

Pleurodesis was considered successful if IPC drainage remained < 50 mL/day for 2–3 consecutive weeks, with radiological confirmation of pleural apposition on CXR and no evidence of fluid reaccumulation, loculated collections, or catheter blockage. Pleurodesis failure was defined as the inability to meet these criteria. Patients who died before IPC removal and before pleurodesis could be assessed were excluded from pleurodesis-related analyses. Recurrence of pleural effusion was identified by reaccumulation of fluid on follow-up imaging.

Post-procedural complications were systematically assessed, including infection (cellulitis or pleural space infection defined by purulent aspirate, positive pleural fluid culture, or non-purulent exudate with pH < 7.20 requiring antibiotics [18]), bleeding, catheter tract metastasis, chest pain, pneumothorax, hemothorax, subcutaneous emphysema, malnutrition, leakage, IPC fracture, dislodgement, and blockage.

Specific complications following pleurodesis were further classified, with symptomatic loculations defined as non-draining pleural effusions due to fibrinous adhesions identified via ultrasound [19]. IPC fracture was characterized by tube breakage during removal due to adhesions surrounding the catheter [19], while catheter tract metastasis was defined as the presence of new, often painful, subcutaneous nodules or masses near the insertion site [19]. Malnutrition was suspected in patients who experienced progressive weight loss exceeding 5–10 kg during follow-up. To account for the confounding effect of fluid drainage, weight loss was only attributed to malnutrition if it persisted beyond the period of active pleural fluid removal and occurred in the absence of ongoing high-output drainage [19]. Chest pain was directly reported by patients following catheter placement, while pneumothorax was diagnosed via CXR performed six hours post-procedure and interpreted together with clinical findings (new respiratory symptoms or oxygen desaturation). Small volumes of intrapleural air likely related to insertion and without clinical correlation were not adjudicated as pneumothorax. Hemothorax was suspected based on clinical signs and confirmed when the pleural fluid hematocrit was found to be at least 50% of the serum hematocrit, consistent with established diagnostic criteria [20].

Catheter blockage was assessed using a saline flush technique, while subcutaneous emphysema was initially evaluated through physical examination and confirmed by CXR if indicated. Pleural fluid samples for biochemical and microbiological analyses were obtained through the IPC itself to facilitate prompt diagnosis and management.

Statistical analysis

Categorical variables were summarized as frequencies and percentages, while quantitative variables were reported as mean ± standard deviation (SD). Group comparisons were performed using the chi-squared test for categorical variables, and either an independent t-test or a Mann–Whitney U test for continuous variables, based on the Shapiro–Wilk test for normality. Survival analysis was conducted using the Kaplan–Meier method with the log-rank test to compare survival distributions between groups. Cox proportional hazards regression was employed to evaluate the association between IPC duration and specific outcomes, adjusting for potential confounders. Statistical significance was defined as a two-sided P-value < 0.05. All statistical analyses were conducted using SPSS software (version 21.0, Chicago, IL, USA).

Results

Patient disposition and characteristics

A total of 91 patients with refractory pleural effusions (PEs) were screened, and 74 patients (62 with MPE and 12 with NMPE) met the study’s inclusion criteria. 10 were lost to follow-up, 4 underwent additional pleural interventions beyond IPC placement, and 3 declined study participation. The cohort included 50 females (68%) and 24 males (32%), with a mean age of 58 ± 15.9 years (range: 17–94 years). Breast cancer was the most frequent malignancy associated with MPE (44%), while heart failure (HF) (42%) was the predominant cause of NMPE. Pleural fluid analysis revealed that 84% of effusions were exudative (Table 1).

Table 1.

Baseline characteristics of patients

Variable	Malignant (n = 62)	Non-Malignant (n = 12)	Total (N = 74)
Sex
Female	45	5	50 (68%)
Male	17	7	24 (32%)
Age (mean ± SD)	57.2 ± 15.00	67.2 ± 18.4	58.0 ± 15.9
Disease
SCLC	6 (10%)	0	6 (8%)
NSCLC	7 (11%)	0	7 (9%)
Breast Cancer	27 (44%)	0	27 (36%)
ESRD	0	3 (25%)	3 (4%)
HF	5 (8%)	5 (42%)	10 (14%)
Other*	17 (27%)	4 (33%)	21 (28%)
Pleural Effusion
Exudative	59	3	62 (84%)
Transudative	3	9	12 (16%)
Lymphocyte Predominant	59	5	64 (86%)

^*Other conditions in the malignant group included metastatic ovarian, prostate, colon, gastric cancer, hepatocellular carcinoma (HCC), lymphoma, and mesothelioma. Other conditions in the non-malignant group included superior vena cava (SVC) thrombosis, liver failure, ovarian cystadenoma, and pleural effusion of unknown origin

Outcomes

Duration of IPC placement

The mean duration of IPC placement was 10.2 weeks overall, with 10.7 weeks in the MPE group and 7.5 weeks in the NMPE group (median duration: 5 weeks (total), 7 weeks (MPE), 6 weeks (NMPE)). The longest recorded IPC placement was 50 weeks in a patient with non-small cell lung cancer (NSCLC). Notably, five patients in the MPE group had their IPC for less than a week due to rapid deterioration and death (Table 2).

Table 2.

Comparison of safety and efficacy outcomes

Variable	Total (N = 74)	Malignant (n = 62)	Non-Malignant (n = 12)	p -value
Duration of IPC Placement
Mean (weeks)	10.2	10.7	7.5	0.37
Median (weeks)	5	7	6
Pleurodesis [1}
Achieved (n)	22	16	6	0.02
Achieved (%)	32%	28%	50%
Median Time (weeks)	9	9	7.5
Recurrence (n, %)	2 (3%)	0 (0%)	2 (17%)	0.80
Symptom Relief (n, %)	63 (85%)	52 (83%)	11 (92%)	0.44
Death (n, %)	54 (73%)	48 (77%)	6 (50%)	0.68
Death with IPC (n, %)	39 (53%)	36 (58%)	3 (25%)	0.90
Survival (n)
1 Month	58	47	11	0.13
3 Months	32	24	8	0.001
6 Months	23	15	6	0.009
12 Months	8	5	3	0.02

[1] Pleurodesis analysis was conducted in 69 patients, as five patients died with the catheter in place before pleurodesis status could be assessed; thus, they were excluded from pleurodesis-related analyses only

Statistical tests used:

• Duration of IPC placement: Mann–Whitney U test

• Pleurodesis: Cox analysis

• Recurrence, Symptom relief, Death, Death with IPC, Survival: Chi-square test

Pleurodesis rate, time to pleurodesis

Pleurodesis success was assessable in 69 of 74 patients, as 5 patients died with the catheter in situ before pleurodesis status could be determined and were therefore excluded from pleurodesis-related analyses. Among these 69 evaluable patients, 22 achieved pleurodesis, corresponding to a success rate of 32%. The median time to pleurodesis—defined as the catheter dwell time required to achieve pleurodesis—was 9 weeks, and it was longer in the MPE group (9 weeks) than in the NMPE group (7.5 weeks). Cox regression analysis revealed that MPEs had a significantly lower pleurodesis rate and a longer time to pleurodesis compared to NMPEs (p = 0.02; Table 2).

Recurrence, symptom relief, and mortality

Following IPC removal, two patients in the NMPE group developed new pleural effusions within 2 weeks. In both cases (one with ESRD and one with heart failure), the IPC-treated hemithorax had achieved successful pleurodesis, and the subsequent effusions occurred on the contralateral side. These events were therefore not classified as failed pleurodesis of the treated side. Symptom relief was reported by 63 patients (85%), with 52 in the MPE group and 11 in the NMPE group. A total of 39 patients (53%) died while IPCs were still in place, including 36 patients (58%) in the MPE group and 3 patients (25%) in the NMPE group (Table 2).

Survival outcomes

Survival rates for MPE patients were 38% at 3 months, 24% at 6 months, and 8% at 1 year, while NMPE patients had significantly better survival, with rates of 67% at 3 months, 50% at 6 months, and 25% at 1 year. These differences were statistically significant (p = 0.001, 0.009, and 0.022, respectively) (Table 2).

Complications following ipc insertion

The most common complication was catheter blockage (16%), followed by chest pain (13%), loculation (9%), and pleural infection (9%). The median time to onset for these complications was 6 weeks for blockage, 7.5 weeks for chest pain and 18 weeks for pleural infection. Cox regression analysis revealed no statistically significant differences in complication rates between the MPE and NMPE groups (Table 3). Three of seven patients with pleural infection died. Two deaths were directly attributed to infection-related complications, while one patient recovered from the infection following catheter replacement but subsequently died from an unrelated cause.

Table 3.

Complication rates among patients with malignant and non-malignant conditions

Complications	Total (n, %)	Malignant (n = 62)	Non-Malignant (n = 12)	p-value
Fracture	2 (3%)	2 (3%)	0	0.53
Blockage	12 (16%)	12 (19%)	0	0.11
Malnutrition	3 (4%)	3 (5%)	0	0.45
Chest pain	10 (13%)	9 (14%)	1 (8%)	0.61
Catheter-Tract Metastasis	2 (3%)	2 (3%)	0	0.54
Loculation	7 (9%)	6 (10%)	1 (8%)	0.93
Pleural infection	7 (9%)	6 (10%)	1 (8%)	0.93
Cutaneous infection	3 (4%)	2 (3%)	1 (8%)	0.73
Bleeding	1 (1%)	1 (2%)	0	0.66

No cases of pneumothorax, catheter displacement, leakage, or subcutaneous emphysema were observed

Chi-square test used for p-value calculations

Impact of confounding factors on pleurodesis rate

Cross-tab analysis showed no significant associations between pleurodesis success and gender or age. However, pleurodesis was significantly more common in transudative effusions (p = 0.01). HF was a significant predictor of pleurodesis success, with 60% of HF patients achieving pleurodesis (p = 0.03). Conversely, cancer presence was associated with a lower likelihood of pleurodesis success (HR = 0.32, p = 0.02) (Table 4).

Table 4.

Factors associated with Pleurodesis outcomes

Variable	Mean Duration(mean weeks ± SD)	p -value (Duration)	Hazard Ratio (HR)*	95% Confidence Interval	Pleurodesis Rate (n, %)	p -value (Pleurodesis)
Sex
Female	10.4 ± 11.6	0.18	0.50	0.18—1.38	16 (35%)	0.46
Male	9.9 ± 11.1				6 (28%)
Age
< 60	10.7 ± 10.5	0.16	1.88	0.76—4.64	10 (29%)	0.54
≥ 60	9.8 ± 12.3				12 (35%)
Pleural Effusion
Exudate	10.2 ± 12.1	0.06	3	0.93—9.63	15 (26%)	0.01
Transudate	10.3 ± 7.4				7 (63%)
Group
Malignant	10.7 ± 12.2	0.02	0.32	0.12—0.86	16 (28%)	0.02
Non-Malignant	7.5 ± 5.7				6 (50%)
SCLC	1.8 ± 0.9	0.09	7.56	0.70—80.94	1 (17%)	0.40
NSCLC	13.4 ± 17.5	0.48	0.50	0.07—3.48	3 (43%)	0.51
Breast Cancer	11.8 ± 12.7	0.17	0.31	0.05—1.67	6 (24%)	0.28
ESRD	11.6 ± 6.0	0.30	0.38	0.06—2.42	2 (67%)	0.18
Heart Failure	8.0 ± 6.3	0.18	2.74	0.62—12.03	6 (60%)	0.03
Other Conditions	9.9 ± 10.1	0.53	0.56	0.09—3.36	8 (32%)	0.98

^*Hazard ratios (HR) are presented with 95% confidence intervals

Cox regression analysis was used to determine factors influencing pleurodesis

p-values < 0.05 indicate statistical significance

Survival analysis

Female gender and MPE were identified as key predictors of survival. Females had significantly lower chance of being survived at 3- and 6-month compared to males (HR = 0.24 and 0.13, respectively), though this difference was not observed at 12 months. Patients with MPE had significantly worse survival at all three time points (3, 6, and 12 months) compared to those with NMPE, highlighting the impact of malignancy on prognosis (HR = 0.06, 0.06, and 0.003, respectively) (Table 5).

Table 5.

Cox regression analysis of survival at 3, 6, and 12 months

Variable	3-Month	6-Month	12-Month
	HR (p-value)	HR (p-value)	HR (p-value)
Sex (Female vs. Male)	0.24 (0.03)	0.13 (0.01)	0.12 (0.16)
Age (< 60 vs. ≥ 60)	0.44 (0.12)	0.67 (0.51)	0.09 (0.08)
Pleural Effusion (Exudate vs. Transudate)	2.16 (0.37)	2.25 (0.51)	20.47 (0.22)
Group (Malignant vs. Non-Malignant)	0.066 (0.001)	0.069 (0.009)	0.003 (0.022)
SCLC	0.000 (0.98)	0.001 (0.98)	0.016 (0.99)
NSCLC	5.74 (0.11)	7.06 (0.20)	175.32 (0.09)
Breast Cancer	0.83 (0.80)	0.67 (0.71)	1.45 (0.87)
ESRD	0.27 (0.26)	0.70 (0.82)	7.82 (0.80)
Heart Failure	4.59 (0.07)	2.85 (0.35)	0.33 (0.89)
Other Conditions	1.60 (0.20)	1.38 (0.23)	1.88 (0.43)

Cox regression analysis was used to determine factors influencing survival at 3, 6, and 12 months

Although the mean post-catheter survival was slightly longer in the MPE group (14.5 weeks) compared to the NMPE group (10.3 weeks), long-term survival beyond one year was not significantly different between groups (p = 0.93) (Fig. 2).

Fig. 2.

Kaplan–Meier Survival Curves. a Duration of IPC Placement. b Overall Survival

Discussion

The management of refractory MPE and NMPE requires a comprehensive, patient-centered approach, considering performance status, prognosis, treatment preferences, and institutional expertise [21]. IPCs have emerged as an effective option for symptom relief and fluid management, yet their long-term outcomes, optimal patient selection, and pleurodesis success remain areas of ongoing investigation [19].

While malignant and non-malignant pleural effusions are inherently different in etiology and prognosis, we included both in this study to reflect real-world clinical use of IPCs. Our analysis preserved the distinction between groups by reporting outcomes separately. The comparative approach aimed to assess whether IPCs provide similar safety and efficacy profiles across varied etiologies of recurrent pleural effusion. We recognize, however, that the small NMPE subgroup represents a limitation and restricts the strength of comparative interpretation.

This prospective cohort study evaluated IPC efficacy and safety in 74 patients, focusing on the primary outcomes of symptom relief and pleurodesis success. We also assessed secondary outcomes, including duration of IPC placement, time to pleurodesis, recurrence, complication profiles, and survival outcomes.

Key findings

IPC placement duration

The average duration of IPC placement was 10.2 weeks, with a range of less than a week (in MPE group) to 50 weeks. some MPE patients required IPC removal within a week due to rapid clinical deterioration, despite the general recommendation against IPCs for those with a poor prognosis (< 1 month) [17, 22]. This finding underscores the need for careful patient selection and prognostic assessment when considering IPCs for individuals with advanced malignancy and limited life expectancy.

Pleurodesis success rate

The overall pleurodesis success rate was 32%, with MPE patients demonstrating significantly lower success rates (28%) compared to NMPEs (50%) (p = 0.02). The median time to achieve successful pleurodesis was also longer with MPEs (9 weeks) compared to NMPEs (7.5 weeks), suggesting that malignancy may negatively impact pleurodesis success, possibly due to tumor burden, pleural inflammation, and altered pleural fluid biochemistry.

Symptom relief and recurrence

Regardless of MPE or NMPE status, 85% of patients reported symptom relief following IPC insertion, demonstrating the efficacy of IPCs in improving patient quality of life. Recurrence of pleural effusions following IPC removal was observed in only 3% of cases, all within the NMPE group, further supporting IPCs as a durable solution for effusion control.

Complications following IPC insertion

The most frequent complications were catheter blockage (16%), chest pain (13%), loculation (9%), and pleural infection (9%), with no significant difference in complication rates between MPE and NMPE patients. Notably, three patients with pleural infection died, all of whom had poor adherence to hygiene and sterilization protocols during home drainage. These findings underscore the critical role of patient and caregiver education to prevent IPC-related infections and improve overall safety.

Factor affecting pleurodesis

Analysis of pleurodesis predictors revealed significantly higher pleurodesis rates in transudative effusions (p = 0.01). HF was associated with a greater likelihood of pleurodesis success (60%, p = 0.03), while malignancy was linked to lower pleurodesis rates (HR = 0.32, p = 0.02). These results suggest that IPC-induced pleurodesis may be more effective in NMPE patients, particularly those with HF-related effusions, aiding in treatment planning and patient selection.

Survival analysis

Survival was significantly lower in MPE patients at all time points (3, 6, and 12 months, p = 0.001, 0.009, and 0.022, respectively), emphasizing the negative impact of malignancy on long-term outcomes. Female gender and MPE were both associated with worse survival, with women experiencing lower 3- and 6-month survival rates compared to men (HR = 0.24 and 0.13, respectively). The observed association between female gender and lower short-term survival may be confounded by the high prevalence of breast cancer among female patients in this cohort, many of whom presented with advanced disease. Importantly, IPC duration was not associated with long-term survival beyond one year (p = 0.93), suggesting that catheter presence does not influence overall prognosis. The lack of association between IPC duration and long-term survival suggests that catheter presence is not prognostic in itself, but rather reflects the patient’s underlying disease trajectory and functional status.

Comparison with previous research

In this study, pleurodesis was adjudicated only when radiologic evidence of pleural apposition was present, a conservative approach that emphasizes consistency and rigor. Compared with more permissive imaging criteria reported in large trials such as IPC-PLUS (< 25% residual opacification) [23], this definition may have contributed to lower observed pleurodesis rates.

For NMPEs, this study’s 50% pleurodesis success rate is comparable to the 51.3% success rate reported in a 2017 meta-analysis. Moreover, catheter-related complications (18% of total cases) in this study were similar to the 17.2% overall complication rate from prior research, though specific complication types varied [24, 25]. This study found a median IPC placement duration of 7.5 weeks, which was slightly longer than the 6-week median previously reported. Conversely, the median survival time (2.5 months) was shorter than the 3.2-month survival observed in prior studies, which may indicate differences in patient selection, disease severity, or follow-up duration. Despite this, symptom relief rates remained consistently high (92%), closely matching previously reported outcomes (93.2%), reinforcing the palliative benefit of IPCs in NMPEs. This study observed a higher recurrence rate (17%) in NMPE patients compared to previous research. The reasons for this discrepancy are unclear, but differences in patient characteristics, pleural fluid biochemistry, or IPC management protocols may have contributed. Notably, pleurodesis success in this study was not associated with age or underlying disease, except for malignancy, which significantly reduced the likelihood of successful pleurodesis. This contrasts with some earlier studies that suggested underlying disease may influence pleurodesis outcomes, particularly in NMPE cases [26]. These findings reinforce the effectiveness of IPCs in managing NMPEs, while also highlighting variability in pleurodesis success and recurrence rates across different patient populations.

For MPE patients, our study reported a pleurodesis success rate of 28%, lower than the 50% success rate observed in a 2011 systematic review [27]. Randomized controlled trials evaluating pleurodesis outcomes with IPCs have reported variable success rates. The TIME2 trial reported a spontaneous pleurodesis rate of 51% in the IPC group, although pleurodesis was a secondary outcome [28]. More recent trials have focused on drainage strategies to enhance pleurodesis. The ASAP trial demonstrated that daily drainage significantly improved pleurodesis rates (47%) compared to every-other-day drainage (24%) [29]. Similarly, the AMPLE-2 trial showed that aggressive daily drainage resulted in higher autopleurodesis rates both at 60 days (37.2% vs. 11.4%) and at 6 months (44.2% vs. 15.9%) compared to symptom-guided drainage [30]. These findings underscore the importance of drainage protocols and patient selection in achieving successful pleurodesis, which may partly explain differences across studies.

This study also differed from a 2019 study in the most common cancer origin. Breast cancer was the most prevalent (44%) in this study, compared to lung cancer (49%) in the previous research. Interestingly, this study observed a higher median survival time after IPC placement (248 days) compared to 141 days in the 2019 study. This study also achieved a higher pleurodesis rate (28%) in MPE patients compared to 16% in the previous study [17]. The reasons for this difference warrant further investigation, but it could be due to variations in patient characteristics or other factors not accounted for in this analysis.

The results regarding the relationship between underlying malignancy and pleurodesis success in MPE patients differed from a 2015 study. The previous research suggested breast cancer patients had a higher likelihood of successful pleurodesis compared to other malignancies. In contrast, this study did not find a significant association between the type of malignancy and pleurodesis success [31]. Apart from tumor type, higher pleural fluid pH, higher glucose levels in the pleural fluid, persistent lung re-expansion postoperatively, and low volume of effusion before pleurodesis are among the most commonly reported factors associated with higher pleurodesis success rates in other studies [32].

Unlike a 2023 meta-analysis, which reported infection (5.7%) as the most common IPC-related complication, this study identified catheter blockage (16%) as the leading complication, followed by chest pain (13%) and pleural infection (9%). The higher complication rate observed here suggests potential differences in patient selection, catheter management protocols, or institutional practices, emphasizing the need for further standardization and education [33].

This study did not observe any significant differences in catheter-related complications between patients with MPEs and NMPE, which aligns with a 2023 retrospective study on 71 patients. This consistency strengthens the notion that IPC complications may not be directly influenced by the underlying type of PE [34].

Strengths and limitations

This study provides a direct comparative analysis of IPC efficacy and safety between MPE and NMPE patients, contributing novel insights into patient selection and treatment optimization. By systematically evaluating pleurodesis success, symptom relief, complication profiles, and survival outcomes, this research enhances the existing evidence base. Unlike many previous studies that focused predominantly on malignant pleural effusions, this study also incorporates non-malignant cases, offering a broader perspective on IPC outcomes across different patient populations.

Several limitations should also be acknowledged. The NMPE subgroup was relatively small, which reduces the generalizability of findings and limits the strength of statistical comparisons. Some follow-ups were performed via telephone with relatives, introducing the possibility of recall bias or missing data. Symptom relief was assessed through structured patient reports rather than validated dyspnea or HRQOL instruments, which limits objectivity. No formal sample size calculation was performed; however, all consecutive eligible patients during the study period were recruited, reflecting real-world clinical practice. The conservative, weeks-based definition of pleurodesis used in this study may also have led to lower pleurodesis rates compared with shorter criteria used in randomized trials. In addition, several prognostic variables that may influence pleurodesis success such as pleural fluid pH, glucose levels, lung re-expansion status, tumor burden, and anti-cancer treatment regimens were not systematically analyzed. Variability in patient selection and drainage protocols may also have contributed to differences in outcomes, including the higher-than-expected rate of catheter blockage. Finally, the small NMPE subgroup size may have limited the detection of rare complications.

Future research should incorporate larger, multicenter cohorts with standardized drainage protocols and more detailed pleural fluid analyses to validate these findings and refine patient selection criteria.

Conclusion

In this prospective observational study, IPC use in patients with recurrent malignant and non-malignant pleural effusions was associated with symptom relief in most cases and successful pleurodesis in a subset of patients. While the pleurodesis rate and complication profile differed between MPE and NMPE groups, IPCs demonstrated acceptable safety and efficacy in both populations. However, the pleurodesis success rate in MPEs was relatively low, and recurrence was observed in a small number of NMPE cases, warranting cautious interpretation. However, due to the lack of a comparator arm, our findings should be interpreted descriptively, and no recommendations regarding treatment selection can be made. Further randomized trials are warranted to define the optimal role of IPCs in different pleural effusion subtypes.

Abbreviations

CXR

Chest x-ray

FDA

Food and drug administration

HF

Heart failure

IPC

Indwelling pleural catheter

NMPE

Nonmalignant pleural effusion

MPE

Malignant pleural effusion

PE

Pleural effusion

U.S.

United states

Authors’ contributions

R.M. contributed to project administration, supervision, and manuscript reviewing and editing. H.K. contributed to conceptualization, supervision, and manuscript reviewing and editing. G.R. contributed to study design, data collection, manuscript drafting and manuscript reviewing and editing. N.K. contributed to data curation, conceptualization, and manuscript reviewing and editing. K.S. contributed to manuscript reviewing and editing, data validation. A.S. contributed to methodology, statistical analysis, and manuscript reviewing and editing. H.R.A. contributed to study supervision and manuscript reviewing and editing. S.M. contributed to data collection and manuscript reviewing and editing.

Funding

This study received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Data availability

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

This study protocol was reviewed and approved by the Institutional Review Board (IRB) of Tehran University of Medical Sciences, approval number IR.TUMS.IKHC.REC.1402.472. The study was conducted in accordance with the ethical principles outlined in the Declaration of Helsinki. Written informed consent was obtained from all individual participants (or their legally authorized representatives) prior to their inclusion in the study.

Consent for publication

Not applicable. This manuscript does not include individual person’s data in any form (including images, videos, or details).

Competing interests

The authors declare no competing interests.